"The only solace--and it is slight--is the knowledge that the great majority of these were aborted by Leftist mothers, and hence the potential growth in numbers of the Left has been reduced."
You make it sound like liberalism is genetic.
Not genetic. But by and large we tend to believe as our parents believed, even if we might have a temporary spate of "rebellion" against them.
This isn't true in every case, but it is true on the whole.