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There have been instances of biological twins where one winds up with autism and another doesn't. So to the extent that autism has a genetic component - it is j

• azakai 10y ago
  That does support non-genetic factors to some extent, but the existence of such twins matters less than their frequency, because twins don't always have identical DNA (mutations can occur after they separate).
  • SomeStupidPoint 10y ago
    Also, even with identical DNA, that doesn't mean the twins will be exactly identical: if things like fingerprints are only very similar instead of exactly matching, then there's reason to think that the fine brain structure can vary as well -- perhaps enough to straddle sides of a disorder. So in addition to twin frequency, it would be worth analyzing twin spread: what is the variation in the behavior of twins (in the background), and is the spread in autistic/non-autistic twin pairs statistically similar, ie, are we just selecting for normal, expected variation that happens to fall close to a boundary?
  • gertef 10y ago
    If autism is caused by an individual mutation (not alredy present in the parent genome) it would be amazing that the mutation is so common, but not currently of a known form (like trisomy).
    • roywiggins 10y ago
      It could be that there are many genes and many mutations possible to cause it, which means two people with autism would almost certainly not share the same mutation. This would make it quite difficult to work out what the mutations are. (There is one mutation that causes something like autism, fragile-X)
• gertef 10y ago
  you mean "identical". both identical twins and fraternal twins are biological twins.