@Emim It's such a new frontier. The most common known genetic link are the BRCA1 & 2 genes. There are a number of others which are quite rare. My sister was tested in 2014 or 2015 for the BRCAs & Li Fraumini, but the CHEK2 mutation test has come about since she died.
I don't know what the costs associated with the BRCA genetic testing are. I saw a private genetic counsellor and the cost for the test was $400.
With your family history it sounds like it would be worthwhile. Do you have children? There are implications. It's complicated eh? Let me know how you get on. K xox