Британские ученые посчитали

The paper finds evidence that having daughters makes people more sympathetic to left-wing parties. Acquiring sons, by contrast, makes individuals more right wing. Ceteris paribus, in our panel data, every extra daughter (or son) leads a person to be approximately 2 percentage points more likely to vote left (or right). Our data come principally from Great Britain, but we show that the basic result can be replicated for German microdata.

https://www.mitpressjournals.org/doi/abs/10.1162/rest.2010.11436