I've never dated so I can't say from experience, but if he's got more in common in relating to things with my dad than with me, he might be too old for me.
I adore my dad and it is a
requirement that my father approve of and get along with whatever man comes into my life. However, as much as I'd like to say age doesn't matter, I'm not sure I could bring myslef to date someone only a little younger than my parents. I'm not going to say a cutoff, because "who knows", but I am saying that it would take a lot of thought, consideration, and persuasion, and even then, I may not go for it.