It's a weird hypothesis. Here is why I think this:
I am a January baby. I love winter. I look better and am more comfortable when I'm bundled up in a sweater and boots than I do in a sundress. Actually, I don't wear sundresses, but this is probably why. My sister Kirsten is also a December baby, and she looks really cute while she skis, etc.
My sister Kylie, on the other hand, was born in June. She doesn't look so good on the slopes (her words, not mine). But put her and my mom (also June) on the beach, and they are totally in their element.
Maybe this is a weird coincidence in my family. Maybe it's really true.