No one.

My older brother. We went to Catholic grade school. I was probably about 9 years old, one year younger than him. I asked him about a few things I'd heard on the schoolyard. He assured me that only Russians did that sort of thing, and when our parents wanted a baby, they just had to ask God. Made perfect sense to me at the time

My best friends Mom. There's a lot more to this story but I answered the question.

My friends Dad . I,ll always remember his opening comments were ' love is a marvellous thing '. I was about 12 or 13 think. We write both a bit bored as we were already 'experts' , and he'd interrupted our construction of a crane from meccano...... Told you I,m old !

I learned on the street where every real American boy should learn.
Seriously, the ninth grade biology class film was so vague, it was useless.
My parents were too simple-minded (really low I.Q.s) and ignorant to have been any help, my mother admitting that my father though women went through a "heat cycle" like animals did when they were married. I am thankful that they never attempted to explain sex to me...I would have been extremely embarrassed. I guess I learned on my own via books in the library, and they were mostly just "plumbing."

I don't remember there being "The Talk" but there was always on-going discussion. At age 5 we had a cow but no milk because she wasn't a mommy yet , so we had to help her with her baby, and all that goes with that, including the calf leaving to become veal. All through growing up it was taught as it came up. The closest it ever came to "The Talk" was "There's no need to rush", "There's condoms in my night stand" and "Pay attention to the other person."