Another beautiful Crossbill comes to drink

It is interesting when you look closely at a Crossbill to see that the beak crosses either from the left or the right.  This gives you the opportunity sometimes to separate individuals.  For example, I don't think that I have seen this bird drinking from my pool before because the previous male birds photographed have had beaks crossing from the other direction. I have read that there is no pattern to this and birds in the same nest can be either lefties or righties! There is probably a gene involved and a pattern of inheritance could probably be worked out. Mendel's theory of genetical inheritance is not difficult to grasp.  For example, some traits can be "sex-linked" meaning that females - in some cases - can carry the gene but only males will show the characteristic or visa-Versa.  Other rules are either dominant or recessive.  I don't believe that any study has been carried out to ascertain what the pattern of inheritance for left or right beaks is? It could, however, just be random, who knows?  This bird (below) is the partner of the male and her beak crosses to the right as well.