Noble of you to take that risk. Tell them, or I will.
Unless their dad was also the product of an incestuous union, the chances of serious complications are minimal.
He might be a little vexed that you kept letting him hump his sister in the mean time.
He might be a little vexed that you kept letting him hump his sister in the mean time. [SEP] Unless their dad was also the product of an incestuous union, the chances of serious complications are minimal. [SEP] Noble of you to take that risk. Tell them, or I will.