The results, drawn from examining 65,000 declared voting intentions over a 13-year period, 1991-2000 ... after factoring out age, education and income, the researchers found that having a daughter shifted allegiances to the left. They checked their unexpected findings against an even larger data base in Germany - and found the same thing.
Also I would guess there will be a relation with having a disabled child, or having a child who is in some other way 'disadvantaged' in the dog-eat-dog world we currently inhabit.
I often think the maniacs saying women are 'asking for it' in rape trials, or that single mothers are sluts (etc. etc.) will change their tune when they have a daughter of their own whom they love and cherish. In fact any man who loves any woman will find it hard to espouse a ruthless right wing ideology IMHO.
Hmmmm, well obviously right wing men can love their wives, but then part of that love is to cocoon the woman inside a protective domestic sphere. I think the thing with daughters is that they have to go out from the family home, into the wider world, and if that world is all about money and rigid gender roles and violence then you start to question those values. You start to put value on things that can't be bought with private money.
Or as they put it women "derive greater marginal utility from public goods like community safety".