The CBC Radio show Ideas posts some of its shows as (limited-time) free podcasts. I've been listening to a new two-part series called Brave New Family that's an excellent exploration of the consequences of sperm donation. The summary:
Sperm donation has proven to be a Pandora's Box. The vast majority of donor dads do not want to be found. In rare cases some children are seeking and finding dad and half-siblings in the process. Science journalist Alison Motluk explores the complex portrait of the brave new family.
Note that these podcasts are only available for a few weeks.