Conservative assumptions explanation: mothers might be less confident about being able to raise a boy well without a father than a girl without a father so they

Conservative assumptions explanation: mothers might be less confident about being able to raise a boy well without a father than a girl without a father so they are less invested in the marriage if it's a girl, fathers tend to feel threatened by a female majority so they are also less invested in the marriage if it's a girl. I feel kind of relieved that this explanation doesn't even survive the subheading "But the difference only emerges when the children are teenagers"