Violent rape was rare, major wars and migrations like the indo-european invasions, mongols, conquistadors et cetera.. were rare events with centuries or sometimes millennia between them. Minor wars where there was less imbalance in power between 2 polities did not affect the civilian population as profoundly since they had adapted to them.

There is also the problem of child mortality in the past, in a wartorn country faced with famine and without the support of a father it is unlikely they'd reach adulthood. Whatever genes made reproduction and survival more likely during these times only gave that advantage for a very short time and were mixed within the genes of the successful tribe.

"Coercive" rape was more common due to arranged marriage and women being dependent on men economically, but then these were vastly different cultures to our own and highly religious. This was by far the most common and longstanding form of rape that resulted in offspring that reached adulthood.

However in the past dowries were common, implying marrying off a daughter was a privilege, a way for a family to ensure her long term welfare and build alliances, and women raised in these societies often hoped to be married to a man of means rather than end up a spinster, a prostitute or marry a man below their station.