The puzzle of lefthandedness
Rik Smits presents an interesting theory of his own: Left-handedness is a side effect of identical twinning. He explains his ideas this way: When the embryos split at an early stage in the pregnancy -- around the first week -- this division would result in identical twins. And twinning may give rise to minor mirror-imaging effects, including left-handedness. But Smits suggests that most embryo splits don't always result in two viable fetuses, and the process often goes wrong. He proposes that perhaps a left-handed fetus survives and is born while the "clandestine" twin, the rightie, is lost early in the pregnancy, before would-be parents know of its existence.Not sure about this - it would seem there is no particular advantage to being the left or the right handed twin. Many MZ womb twin survivors are right handed, but they may be mirror twins also.
We can never know how many right handed people are MZ mirror wombtwin survivors - unless of course we ask them how they feel about being a twin - they can usually tell if their twin was MZ or not, its amazing! They may be the ones who have a preoccupation with mirrors, and there are plenty of those!