In the English speaking countries of the 20th century, circumcision typically required the consent of one or both parents.
Lets look at some possibilities. Circumcision is sometimes:
(A) was fairly common in the days of near universal mutilation. Sometimes an adult has it done to them while undergoing another operation. Its very cruel to do something to someone (especially when it permanently alters their body) when permission was not (but could have been asked) or against their wishes.
(B) There are people who have had a son born and the doctor has asked suggestively, "Would you like him circumcised?", without giving any further information. This was quite common a few decades ago. Mothers who have just given birth are often tired, drugged and highly suggestible. Also there is the mentality that the doctor knows best, so the doctor makes the circumdecision.
(C) is very common. A information sheet may be written by someone who has a financial incentive in mutilation, enjoys doing them, has been doing them for years, has an emotional investment in them etc. etc. Sometimes an attempt to balance pros and cons is highly distorting. These information sheets don't stand up to scrutiny.
Circumcisors are fond of downplaying the frequency and severity of risks. "Complications are rare and only minor". Many times the possibility of complications is never mentioned. Doctors sometimes say they downplay risks and consequences so as not the worry the parents.
Superficially this may seem kind, but it is actually doing a great disservice to the parents as it is giving them faulty information to base their decision on. It leads to uninformed consent which in many contexts is unlawful. A more important reason for the "don't worry" attitude is to protect the ego of of the circumcisor. Also, circumcisors sometimes rationalize by saying to themselves "only unskilled operators have complications, I am skilled, therefore I will not create complications".
(D) Doctors would surely know fully well that the typical parent knows sweet FA about mutilation. Parents typically think much less is involved than actually is. Some parents think it is no more involved than cutting the umbilical cord.
(E) Informed consent is only possible if a person receives information of all risks and consequences of a procedure. In practice, information received is usually far short of this. Uninformed consent is not consent, and when this happens with an adult, an assault charge is possible.
As with (A),(B) and (C) there have historically been many times parents have hardly been involved in the circumdecision.
Regarding (D), Parents who request circumcision range from people who have spent much time over the decision and only reluctantly, to parents (or a parent) who came to a conclusion very quickly. There appears to be a large subgroup of parents who fall into the latter group.
Sometimes these parents are so determined they go from doctor to doctor until they find one who doesn't refuse to do it. Munchausen syndrome by proxy?
Some people get angry when challenged with their circumdecision. They may use body language, rudeness, voice tone, sarcasm or attempt to intimidate anyone else who raises the slightest doubt in them.
Its like, they have got a Pandora's box full of guilt , doubt, grief and other feelings they don't want to know about. "Get off my back!"
A popular cliche is "Its the parents right to have a circumcision done for whatever reason." This is like cutting off your nose to spite your face, except you are having the end of your child's genitals cut off. "Whatever reason" means no reason.
A similar cliche "it is an individuals free choice", which of course conflicts the right of the child/future man to make that choice for himself.
Perhaps what they are really saying is "The child is my piece of property and I reserve the right to abuse him, and its nobody elses business."
The average child or teenager does not care if their genitals are like his fathers. Meaningless to the child, but of emotional benefit to the parent. If Dad had more awareness of his feelings, he might discover he is envious of a child having something he doesn't.
People who aggressively support mutilation are sometimes surprisingly ignorant about the issue. They don't know what the purpose of a foreskin is, ts structure and function, the consequences and risks of its removal.
On the Internet there are numerous websites on this issue, most of them making a very strong case for not interfering. A large number of people express pro-circumcision opinions on posts, but don't seem to have done much research.
Fathers who were cut themselves may collude with the circumcisor. One said "It was good enough for me, so its good enough for him." What they are really saying is "I had to go through that torture, so my son should too". It feels a little better when someone else has to suffer. Its not uncommon for a father to support circumcision and the mother to oppose it. Sometimes its the other way round. One woman once said to me with great anger, "I had my boys done". Another reason why (in the USA) the requirement for 2 signatures would be better than one.
Adults carrying anger, for whatever reason may be more prone to elect for circumcision.Some people might prefer to follow what they think the majority of people are doing. They figure that if lots of people are doing it, they cannot go too far wrong. Another reason might be conformity helps people feel more connected to other people. This is a dangerous assumption and can lead to an Emporers new clothes or the blind leading the blind situation.
Letting other people do your thinking for you, is no guarantee that they will do it well or in your interest.
A related idea is that when any system is in place some people will defend it, regardless of the what the system is. This is different from preserving or defending a system on its merit, it is done regardless of its merit. It is more to do with factors such as the security of keeping things the same and avoidance of the fear of change, and the avoidance of the responsibility of decision.
These are are some of the factors which may have helped preserve the pesecution of alleged witches in Medieval Europe (though there are other factors at work too in that case).
Irrational fear can be a factor in the circumdecision. Unscrupulous circumcisors prey on this.
There is a phenomenon called 'Unconscious child rearing'. A basic means bringing a child up in the same way that you were brought up. Its called unconscious when its done mechanically and without awareness.
Its important in the area of punishment, a parent screams at a child because they themselves were screamed at, even though might not remember it, because thats the way their mind is programmed.
Its well known that parents who abuse their children were abused themselves. Abuse seems to work in two ways. People who have remained sensitive and understand and felt their abuse tend to have the approach "I could never do this to a child".
People who have become insensitive, unfeeling, callous etc. perpetuate the abuse to next generation.
There was a child who was locked away for many years and was fed on bread and water who became an archetype of abuse. It has been suggested that some mothers who present their child to doctors with false complaints are abusive. It was theorized this was because of unconscious anger. It was not suggested that the resulting unnecessary surgery was due to doctors being abusive. In these case the doctors are more responsible than the worried parent.
A person might have a view that mutilated genitals look better in their view. This is clearly totally subjective. It is unethical and abusive to perform cosmetic surgery on a person without their consent.
Sometimes its the circumcisor who holds the view that mutilated genitals are aesthetic. Many circumcisors site this as a reason in favour of circumcision. To impose your aesthetic view on someone else child is unethical and abusive.
The term "health benefit" is to be preferred to "medical benefit" as it suggests a real rather than theoretical benefit, and the term medical benefit may be an unconscious reference to something being of benefit to doctors and the medical system.
Many health reasons are highly irrational. Many supposed benefits don't apply until the child is an adult and sexually active. Claims that circumcision can prevent stds, cervical cancer in women and penile cancer are irrelevant because its up to the individual to decide for himself when he is an adult. In any case the above claims have been refuted.
It would seem these reasons have a useful purpose though. They allow that person to feel better about themselves, because the circumcision is supposedly of benefit to the child. The real reason for supporting circumcision is one or more of the peverse ones.
A more rational reason is the claim that circumcision somehow is of health benefit while the child is stll legally a child.
Some parents might request circumcision because they believe that is of health benefit to a child under 16 (or whatever tha legal age is). This is the most ethical reason, though some surveys show that only a minority of parents give this as the reason.
Nonetheless given that the idea that circumcising for reducing UTIs does not stand up to scrutiny. It could be that UTIs in an intact boy happens because the foreskin has been forcibly retracted by an adult. Prophylatic surgery is not normally performed on healthy tissue. Medical associations don't recommend routine circumcision. UTIs in girls are more common than in intact boys. This reason may be a mask for other reasons.
Some parents might have opted for circumcision because of misleading information they have been given.
There are some parents who would never have a child circumcised and others who do it and don't give it a second thought.
What are the differences between these groups?
Just as with circumcisors, parents who opt for circumcision will have inner emotional conflict. This happens because the mind is trying to override the inner emotional intelligence, which is revulsed and disgusted by circumcision.
Emotional conflict may tend to be lower if religious reasons are involved. Anxiety is low because the religon has made the circumdecision for them, the parents have opted out of the decision making process.
More insensitive people are less aware of this emotional conflict. If they are of little education and prone to bigoty, they are more likely to accept predjudices for a rationale.
More sensitive people are more aware of this emotional conflict. If they are of high education, they will need more complex rationales.
I'm not aware of research on why some parents choose to and others do not.
A speculative list of possible things to explore could include: