In addition, children don't have to come from your body for you to love them. Look at the parents out there who adopt children... I would hope that no one would suggest that the parents don't love an adopted child as much as they would their own biological child on the basis of where the kid came from.
Some people may only be able to love one kid. Some people may not be able to love any kids. Some people may be able to love more than one kid. Some people may only be able to love one partner. Some people may not be able to love any partners. Some people may be able to love more than one partner.
Being poly doesn't have to ever include having sex with the people you love. Polyamoury is just that... poly (many) + amoury (love). I know quite a few poly people who do not have sex with the people they love. It all depends on life situations and vows that have been taken.