I always suspected (as I did with many of this professor's proclamations) this was wrong, but I never was able to prove it...until I became a father myself. Because there's utterly no doubt this kid is mine.
How do I know? Several ways, actually. There is a definite physical resemblance. Many people have told me she looks very much like me. I would then do the typical self-deprecating thing and exclaim "Poor girl!," "But that can't be...she's cute!," or something similar. In fact, some of my "friends" are saying similar things to this day.
My next clue was her feet. She has DuBose toes. My whole family was blessed with extremely long (bordering on finger-length) toes. Sylvia has them too. I have freakishly long toes, and I sometimes amuse myself by using them to pick objects off the floor...which amuses myself greatly. Lately, Sylvia's been doing the same thing...when I change her, she'll grab the clean diaper with her feet and yank it out of my reach...the little imp.
Then there's the gestures. When she was a few months old, I was trying to make her laugh while she was sitting on my lap. She gave me a look of withering contempt before sighing and hunching her shoulders. My blood ran cold...I'd seen myself doing that exact gesture over and over. I could see Sylvia inflicting upon me every single annoying thing I did to my parents.
Then there's music. Shortly after learning to crawl, she started going up to my living room guitar and bashing the strings. She still does this. It makes my heart soar every time I hear it. Lately, she's discovered that if she howls into one of her hollow plastic toys, it adds reverb. I also love this beyond words...because it proves she, just like me, also loves effects.
Of course, there's plenty of my daughter which does not come from me...her piercing eyes and her cuteness, just to name a few. But it all adds to the fun.
Life, 1--pseudo-psychotic theory professors, 0.