This is a topic that comes up here on the forum every so often, and it seems that most members are quite torn on the topic. Many feel tickling IS hereditary, and can be inherited from other family members. Some, though, feel you can not pass on personality traits, or "kinks" in this case.
Personally, I feel it IS hereditary. My uncle is a known tickle fetishist. I believe I inherited my tickling interests from him. I knew by the age of 5 already that I enjoyed tickling more than what was normal, and no one in my life previous to that stage had tickled me enough for it to have been a 'conditioned' effect. It just HAPPENED. So I am positive I was genetically wired this way.
Same with my fiance, and fellow TMFer Lazarus. By preschool age he already had a strong interest in womens feet, and tickling them. Also not something he was conditioned to take notice of. His bitch ex (who did not approve of Lazzy's tickling fetish) blurted out to his Dad one day during a conversation: "Are you into tickling too?" - much to Lazzy's dismay, since he had never told his father of his interest in tickling. His fathers reply? "As a ler, or a lee?"...spoken with an evil sadistic grin. Safe to assume his father has at least a minor interest in it.
Both Lazarus and I have passed it on through our genes to our kids as well. My one daughter is a severe ticklephile, and his oldest son also has a healthy, beyond normal childhood playfulness, interest in it.
So in closing, yes, I do believe an interest in tickling can be passed on hereditarily.
Mimi 🙂