My Lesbian Sister

My Sister Heidi is a lesbian and is in a relationship with Helen. Both are 25 and fairly attractive, those they don't dress to impress males. Always loose clothing that dosen't show their figures. Anyway they decided to marry each other and Heidi wanted to start a family straight away. So she asked me Andrew 22 to donate sperm so Helen could get pregnant, I said I would. So they told they let me know went it would be need, Helen didn't have brother or close male relatives to get to donate for Heidi to get pregnant. They asked a friend of theirs to donate for her. The day they pick for their impregnating arrived, they both were out shopping for the upcoming wedding. Their Steve drop off a jar of sperm for Heidi and then he went to work as airline steward. I put the jar on a small table near the stairs to the bedrooms. Then Bobby my dog came into the house and laid down the cushion that Tabby Heidi cat slept on at night. Then Tabby came into the room and went after Bobby and he took off and bump the table and the jar smashed. I cleaned up the mess and went into the kitchen and got old jar and made my own donation to replace the lost one. Shortly after they both arrived home, I gave the jar and they asked me for my donation. I said I haven't been after to do it as the pets were playing up again. Heidi asked Are you having trouble doing it, do you want some help. Help I replied What kind of help, we could undress and makeout in front of you and it might get you going. Yes That might work I said, we call you up to my room after we've delt with Steve's donation. So I sat watching TV for about or so, then Helen down the stairs nude and told to come up to their bedroom. When I got to the room, Heidi was on the bed with hips raised up on pillows. Then they told to undress after which they started making out together. I watched and got hard and started to stroke my cock, but I still didn't cum and they decided to take over the masturbating of me and they both even sucked my cock. Soon I started to get close to cumming really close, then we realised they we hadn't got a clean container to put in. Not wanting to waste it Helen stick it in me and do it. So I did, I came shortly after and they were both happy. Over the next couple of days, my conscience was worrying me. So went Heidi was home alone with me I confessed what had happened. She was upset at first, but then well it would probably not work anyway. Most people I know who have done this, had to try 4 or 5 times before getting it right. She told Helen went she arrived home and she just laughed, about 2 months later they both tested positive to being pregnant. Heidi didn't anyone about my sperm donation, just had every test possible and nothing wrong was found. They also told that it hadn't worked and she gone a clinic to get pregnant. Last month they had a boy and a girl 3 days apart and all are doing very well. Helen call me uncledad for Heidi son Andy and just dad for her daughter Angelina. But only when others of the family aren't around.