My mother had been a vegetarian (also ovo-lacto) for almost 15 years when she had me, and then my sisters came three and six years behind me. We ate only vegetarian food at home, since my step-dad was also vegetarian and they both were doing it mostly for moral and sustainability reasons. We did, however, get meat at friends' houses or at our grandparents' houses.
I do remember at a very young age not really liking meat a lot, but that had completely flipped by the time I was about 6 or 7. We still didn't eat a lot, and eating a meal with meat as the main course STILL made my tummy feel funny, but we did eat meat more frequently.
It's prolly more a familiarity thing, and possibly a bit of him only having been exposed to what you ate while you were pregnant. He will most likely grow into liking meat, although some people really never do.
You said he only really eats chicken, but not how often, so it's possible that he's eating enough for it for him to be breaking it down by himself, but sometimes if you don't eat red meat much and you try it, even if you have been eating chicken, it can be hard on your stomach. He might be noticing that effect when he does try it, and avoiding that meat because of that. You will probably have an easier time if you ease him into it, giving him smaller amounts with increasing regularity.
This is all of course only if you really want to encourage him to eat meat. It will not hurt him to not eat it, as long as his dietary requirements are being met elsewhere. In fact, it might be better for him to NOT get used to eating huge hunks of meat early in life - you might save him the heart problems and obesity issues later in life that so many Americans suffer from.
Congratulations on not having to force-feed his veggies to him! That's a win-win situation if I ever heard one.
