I do not feel particularly qualified to argue either way, but methinks social bond is a result of experience rather than genetically programmed. The fact that most men do not seem well connected to their children may be a result of low social value of male parenting, little time spent with the children, etc. Conversely, if women indeed have a stronger natural bond with the children, that needs to be positively demonstrated, among other, by ruling out any 'social' factor (such as gender roles, expectations, time spent with children, etc.).
Nancy Chodorov, if memorry serves, offered a still alternative explanation; the differences are neither 'learned" (in a traditional sense) nor genetic, but they are deeply ingraimned in how male and female personalities are formed; girls identify with their mothers because women are the only adult figures around them most of the time, whiole boys essentially lack an adult figure they can identify with (since most fathers do not participate in child rearing), so they develop their personality by negating female traits they observe in their mothers. Nice story, although nearly impossible to verify empirically.
Regards,
Wojtek