Well... your eyes may not, but at least your mirror reflection must match!

Genetics' mechanism is fascinating. Genes come in pairs, one gene may be dominant, and override the other gene, which is recessive. When it comes to eyes color, the "brown" gene is dominant, and the "blue" gene (not to be mixed up with "blue jeans") is recessive.

For a child to have blue eyes, both parents must have at least one blue gene, and the two of them in turn must be combined. The child will have brown eyes in all other possible configurations: namely blue-brown, brown-blue, and brown-brown.

However, the probability varies according to the parents' gene configuration. They must provide each one blue gene each, but the global probability raises to 50% if exactly one parent have the configuration blue-blue, i.e. have blue eyes.

Therefore only when both parents have blue eyes, all of the children will (almost) inevitably have blue eyes since there is no dominant brown gene present to mask the recessive blue gene.