Males. I think just like with humans, the males are just more needy, and they need a mommy to take care of them
Diesel is so needy, he always has to be snuggled right up in my neck. He is SO submissive to me too. Lilly is super happy go lucky with me. She likes to be held and sort of stand guard on my lap, but not melt into me the way Diesel does. She also humps my female Shih Tzu for some reason.