As discussed, it was a sign of the times AND the Business. Sure, he loved his children but didn't ask what was purchased for Mary because he simply didn't think about her in the same way as Anthony. And yes, FFC/Puzo purposely wrote the line that way to put across a specific point. Girls were nice, but window dressing. Sons were to be raised and educated if not to run the Family Business, then to achieve even greater heights as 'Governor...Corleone' or 'Senator...Corleone'.

For men like Michael in the 1950's, the more sons, the greater the chances of that dream becoming reality (even though it didn't work quite that way for Vito's children)!

Apple