I just read Chapman's "The Five Love Languages," which gave me some food for thought. The theory is that there are 5 languages of love, and each language can have many different "dialects."
I am wondering if mixed messages we get in our upbringing (nurture) isn't part of the reason why we are drawn to speaking different love languages with different people.
If you speak one love language with your mom and another love language with your dad, doesn't it make sense that you'd be "bilingual," and that you'd be comfortable communicating with/loving more than one person?
Maybe it's a case of your parents' languages? If they're the same, mono would feel more comfortable, and if they're different, poly would?
This is off the top of my head, just read the book yesterday