Many know that certain personal characters are dominated by genes from one parent in color-different families. Actually we used to heard someone said “Your beautiful eyes are just like your mom’s”, “Her teeth are just like her dad’s, and are different from her mom’s great teeth”, even in same color families. How parental gene alleles compete each other in controlling one’s physiological characters is a big puzzle. Now reported in Nature, scientists found one way to explain this puzzle. It is known that methylation controls gene expression.The new study reported that a type of non-coding RNA from the dominate allele controls the methylation of the allele from the opposite sex, therefore silences it.  It’s yet to be determined that this is the case for human.