Thanks in part to 18th-century nuns, we now know that having children and breastfeeding reduces a mum's risk of developing breast cancer for years, even until her kid is well into primary school. Now Australian scientists have discovered how breastfeeding specifically enlists the immune system to protect against an aggressive and hard-to-treat type of breast cancer. You can binge more episodes of the Lab Notes podcast with science journalist and presenter Belinda Smith on the ABC Listen app (Australia). You'll find episodes on animal behaviour, human health, space exploration and so much more. Get in touch with us: labnotes@abc.net.au  Featuring:  Sherene Loi, medical oncologist at the Peter MacCallum Cancer Centre  Extra information:  Parity and lactation induce T cell mediated breast cancer protection  Having children and breastfeeding reduces breast cancer risk by triggering immune system, study finds  This episode of Lab Notes was produced on the lands of the Wurundjeri and Menang Noongar people.