|MadSci Network: General Biology|
Hrm.... This is an interesting idea. But actually no one is yet sure exactly what makes left handedness. So, no it's not brain damage, and no it isn't because of being fraternal (two-eggs) twins, or identical/monozygotic (one- egg) twins. Though, if you have a relative who is left handed you have a better chance of being left handed than if you don't. Which means if one identical twin is left handed it is most likely that the other one will probably be left handed as well. As far as fraternal twins go... there is no greater likelihood that one or the other will be left handed. Oh... and if you run across the story that left handed people die earlier, that isn't true either. There are fewer left handed people as you look at older people because schools were more strict about "making" left handed people into right handed people than they are now. Well, I hope this helps. Greta Hardin
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