Is a guy who does a single, childless woman a “favour” so she can become a mother in Israel and agrees to act as a “known sperm donor” in medical procedures (in contrast to an anonymous sperm bank donor), at risk of having to pay child support later, even if she promises not to make any financial or other demands regarding raising the child, but changes her mind and sues him?

Yes! In 2015 Hadera Family Court in Israel held in a case where it was proved that a man was the biological father of a child by acting as a known sperm donor, without an agreement about shared parenting, between him and the single woman recipient, who became a mother,he was obliged to pay child support, for the child’s basic needs, at a reduced rate, of 1,500 NIS a month, including housing and associated costs,and 25% of any additional costs.