Impregnate Your Twin Sister

You are awoken one night by shouting outside the front of Mom and Dads house; its your sister having an argument with her husband about something at 1AM. She comes in and explains to you, Mom and Dad that she just needs to stay for a few nights, as she wants a divorce because her husband doesn't want her to be pregnant and your sister is desperate to become a Mom. All she wants is to have a little one before she gets too old, her own husband is saying no, and as her brother, you are outraged by this! You try your best to light heartedly comfort her, but she is just so upset and a little bit tipsy. You try to make her laugh like a good twin brother and it kinda works, but before you know it you've offered to get her pregnant yourself! If her useless husband won't be man enough to fuck her without protection, then you certainly will.