From evolution point of view can we explain as to why mothers care about child rearing more than fathers? Is it Social phenomenon or genetic phenomenon? Are mothers hard wired to take care of children more or they are socially forced to do so?
Because mother invest the most material and time into producing the offspring, so there is a stronger pressure on them to not waste it. Males can go impregnate other females so there is a stronger possible disadvantage for child rearing, few mates thus fewer offspring. Whereas a female can't have more offspring by finding other males while currently carrying offspring so they are forced to sink a lot of time and energy into the offspring. So evolution strongly disfavors females who waste those resources by abandoning the offspring.
Strong K strategists like human tend to override much of this becasue of how much investment the offspring need. So there is a strong pressure for the female to only accept mates that can provide a great deal of resources, including time. And males can seriously hurt the chances of their offspring surviving by abandoning them. But there is still more built in investment on the part of the female.
There is one other factor, A female knows who her offspring are, males do not, so the offspring they invest in might not be theirs, so there is a pressure to not put all their eggs in one basket so to speak, this is also why males tend to be more worried about physical infidelity (cuckolding) while females worry more about risk of abandonment (loss of support).
Now remember this is males an females in general, individual species can have different pressures. And remember that humans have very complex behavior so much of this just amounts to tendencies on average, not hard and fast rules.
More on the ethology of mating here. http://www.tandfonline.com/doi/pdf/10.1080/11250008409439461