The science of something as unpredictable as human behaviour is easy to pick apart during cross-examination in court. It’s particularly amusing when your own research is used against you.  This is partly why Professor Michael Lamb, the head of the Department of Social and Developmental Psychology at the University of Cambridge, recently made headlines stateside in the ongoing Proposition 8 trial when he was questioned about research on same sex parents raising children.

But is psychology really a science?  Well, yes, since the top scientific journals publish peer-reviewed psychology papers. But the evidence used in the Proposition 8 case is not as clear-cut as in other fields. For example, the size of an atom in Thailand a century ago is the same as an atom in Cambridge now, but there is not a single equation or code which can be applied to ‘normal’ human behaviour or raising children. What is acceptable varies throughout history and between cultures.

During the trial, the defence lawyer David Thompson claimed “We want to show he [Lamb] doesn’t have any studies that are married, biological parents, and that’s our core argument”. But this ‘control’ experiment referred to by Thompson is an unobtainable ideal.  First, how would you choose and match ‘typical’ married, biological parents, even if you confined your samples to one state, social class or religious belief?  Being married and heterosexual does not equal ‘good’ parenting, and all married, biological parents have different ways of influencing their children.

Lamb’s conclusion that raising well-adjusted children is independent of sexuality may not be airtight, but it is the best evidence available given the variables, and should be sufficient. A defence lawyer will have difficulty questioning the evidence on the dangers of smoking or Thalidomide poisoning, but they will always find flaws in psychology; humans are far too varied and complicated to be reduced to direct cause and effect.