Genomic Imprinting Evolution

Genomic Imprinting is an epigenetic phenomenon that limits expression of a particular gene to either the paternal or materal allele specifically through silencing one allele. (I believe it is through DNA methylation.?)
A new study indicates (according to the synopsis) that not only is genomic imprinting is still evolving in viviparous mammals, it also appears that evolution occurs in a coadaptive evolutionary mechanism. This is somewhat contrary to theories that I had heard before that include that the mechanism allowed males to pass on genetic fitness specifically to male offspring and females to female offspring. I have also heard that the mechanism reflects a competition of interest in males in their offspring and females in their offspring. A male wants large offspring because the male is unconcerned about the maternal investment in raising a more energetically expensive large offspring and the female is opposite.
I am still not sure if I understood the synopsis ( that is written for a general audience) so if anyone has insight.. have at it.
I included the picture because of all the nipples.