Of course there are other factors here as well. Experience, size, etc. In sexually reproducing species, parent and offspring are not identically related. On the other hand, offspring should devalue cost to parent compared to benefit it receives. Lets look at weaning conflict.
Interesting point is that the degree of relatedness determines period of conflict.
In monogamous species we expect shorter of conflict than in polygamous species. In primates, looking at monogamous vs polygamous species, this seems to be the case. Often called the Cinderella Syndrome . Infanticide and Siblicide. A. Already discussed langurs and lions.