My 13-year-old daughter, a fan of all things Japanese, wanted to know her blood type. (Some people in Japan think that blood type correlates with personality types. Jane knows it's bunkum, but it's fun anyway.) I didn't know her blood type, and I forgot mine. Carla didn't know her blood type either. We didn't have Red Cross blood donation cards, because we aren't eligible to donate blood: Carla doesn't weigh enough, Jane is too young, and I "lived a cumulative time of 3 months or more in the United Kingdom" back in the 1980s (I have mad cow prions ready to erupt in my brain any day now, I guess).
I looked on Amazon and, wouldn't you know it, they sell blood typing kits! I ordered enough kits for the family. They cost about $5 each.
The kits come with everything you need: spring loaded lancet, micropipette, stirring wands, cleansing swab, and a chemically treated card to put your blood on. The card has four circles, each of which contains a different kind of serum designed to cause clotting (or not) in your blood sample.
The lancet is a little scary to use. It looks kind of like a tiny tube of Chapstick with a hole in one end. You have to press it against your finger until a spring loaded latch inside the tube releases, slamming a sharp needle into your finger. I went first. The sound it made was worse than the jab. Interestingly, the needle shoots back into the tube after it pokes your finger. What an ingenious device! Here's a video of the same lancet that comes with the kit:
After that, we just followed the instructions for putting our blood on the cards. I have O negative blood (universal donor, but since I'm a mad cow risk, I can't donate). Carla and Jane were both B positive. And now we know. The process was actually a lot of fun. I wish our blood type was something that changed every couple of years, so we had an excuse to do this again. Maybe we will anyway.