Younger Friends?

Whilst we may be programmed to believe that younger friends would be both inappropriate and "wrong" do we actually know this from personal experience of such friendships? I would for these purposes consider younger friends to range between the years of around thirteen and eighteen, I`m in my sixties. Those much more advanced of years I`d for all tense and purposes regard as being of about the same years as me. I even share my house with females aged eighteen to thirty. I believe that age segregation in friendship tends to making for false friendships, but the nature of a friendship must obviously be appropriate. On occasion a reciprocated smile is sufficient on its own to communicate the perfect friendship. Selfless friendship would have a very hard time in ever doing any wrong. There may be hope for grandparents yet! What are your thoughts on this?