What do YOU call your Biological Mother?

So, I was told immediately after I was adopted (as best as they could) that I was adopted at age 3, and have been extremely lucky to be part of an extremely lovely (adoptive) family since I was 3, but until I fell at the age of 18, I'd spent 15 years blaming myself (silently) for anything that went wrong... Even as a highly intelligent child, I just thought I must always have been to blame for everything... It must have been my fault... It was quite literally the Christmas before my 18th Birthday, and with an argument with my Father (my adoptive ones have given me my whole intellectual upbringing, and couldnt consider them as anything but my parents), that I found out that I'd been removed by social service and (kinda) why.... It wasn't my fault... Doesn't change a lot of my personal demons, but yes, it wasn't my fault... I do not have any plans to meet them, and they go by 'birth woman' and 'birth man'.