Rich Morin, writing for the Pew Research Center, summarizes their findings:
Having more daughters than sons and having a daughter first significantly reduces the likelihood of Democratic identification and significantly increases the strength of Republican Party identification.We say where you sit determines where you stand. The sex of your children is no small part of where you sit, your life circumstances, the "hand" that fate has dealt you.
Compared to those with no daughters, parents with all daughters are 14% less likely to identify as a Democrat….[and] 11% more likely to identify as a Republican than parents with no daughters.
The daughters effect is considerably stronger among better educated and wealthier parents. (snip) Farther down the socioeconomic ladder, it weakens to statistical insignificance.