Don't reprimand him badly, as a foot fetish man myself, I know this. If you try and supress it, it will bite you in the *ss later in life, tell him not to, but don't PUNISH him for it
This is a very old post. I'm thankful that my children do not have this fetish as it certainly can cause issues finding anyone else that would want to be involved with it. Perhaps some professional help to overcome it would be helpful.
It's very unusual for someone to like both male and female feet. I love female feet but find male feet very disgusting. From polls I've seen on other fetish websites, almost all of us feel the same way. Your also a very understanding father. If my father had ever found out, he would have beat the crap out of me and committed me to an institution.
I pulled my answer below from another post that I think is similar. My advice is stop making him feel ashamed and start supporting him.
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My son had a fascination with feet his whole life (he's now 30). Please don't make your child feel ashamed of liking feet. I assure you there is no way to remove his fascination for feet and he will continue to look for ways to satisfy his foot fetish regardless of what you do. The more you discourage it the more likely he is to develop unhealthy behaviors, like liking the feet of other sleeping women because he feels that is the only way to 'get his fix" without being ostracized.
Instead, talk to him about it and let him know it is ok to like feet, but also teach him the rules of social etiquette. If he wants to lick feet, tell them that is fine as long as you ask the person first and they agree to let you. But also let him know he is in the minority, just as gay people are, so there may be those who will judge him for liking feet.
Also, don't worry too much about him licking your feet, or the feet of other family members (as long as they give him permission). He will eventually grow out of that. My son used to lick my feet as well as my sisters' when he was young. He stopped around 15/16 when he clearly got more interested in the girls at his school. My sisters and I sometimes joke that we wish he still did it because it was like a free foot massage.
He has grown into a fine man who just happens to like feet. It never even comes up anymore because it is something he keeps between he and his wife. However, he has thanked me before for giving him the confidence to not be ashamed of liking feet. Because of that he had the confidence to tell his wife, when they were dating, and she is very accepting of it.
Good luck.