Basically , their answer is ‘magic’.
Nope. Given Jesus’s miraculous birth, it’s not magic, it’s God’s Holy Spirit. “If it is by means of God’s finger…then the kingdom of God has really overtaken you.”
The Insight Book in general has been refined (not only in the related explanation about Jesus’s perfection in-spite of Mary’s sinfulness.) You will find that in other Bible interpretations and topics, there is very little commentary now except for what can be supported with evidence from the Bible. The Bible does not say how Jehovah did it or why Jesus was born perfect although his mother was a sinner.