Hi Micha,
Only about 5% of breast cancer is genetic so chances are slim that it is genetic, but it is worth speaking to you doctor or oncologist especially if you and your mum were both young when you were diagnosed. They will put you in touch with the genetic counsellor who will look at your family history and then determine if you are eligible for free testing (public, and some States have atrocious wait times) or you can pay between $3500-$5000 (out of pocket) to have it done privately. If it just you and your mum diagnosed chances are you won't qualify for the free testing. I was 41 and my mum 42 and that was not enough of a link, my genetic counsellor pushed for more family information (they normally just go to granparents) - my BC was pretty much the same as my mum's even in a similar location in the same breast. Turns our my great aunt also being diagnosed late 40's was the clincher for testing and in my case it came back BRCA2+ve. Yet on my husbands side they have 4 generations of women diagnosed in their 30's and 40's and it came back negative so you really don't know.
It is also a case of be careful how much information you wish for, from a medical and preventative point of view I am grateful but I also miss the ignorance. There was a big cost finding out, both financially and emotionally, the knowledge of the mutation also meant going through multiple surgeries; a double mastectomy and reconstruction, full hysterectomy with ovaries and tubes. I have to look at my 11 and 14 year old daughters knowing there is a 50% chance they are going to have to plan their lives around the possibility that they may need to have their ovaries removed by the time they are 40 and consider prophylactic mastectomies at some point as well. I have had to put all of my aunts, uncles and cousins through the agony of deciding how much they want to know and whether they want testing - they will test the older generation first, so they would do your mother before you. My mum's sister came back -ve and my uncles have been avoiding it. My younger cousins have been told to organise life insurance now before they have to consider testing as BRCA+ve is considered a pre existing condition and insurance companies treat you like you have cancer even if you don't ever develop it. There is so much more to BRCA+ve to consider and once you've opened the box you can't put everything back inside again. If it something that really bothers you then go for it, but if it just a curiosity then I would personally advise treating it like one of lifes mysteries. Good luck, Jen