Instead of artificial insemination, the girls went with in vitro fertilization to conceive Gus. But what Lindsay doesn't know is that the same day that they were extracting her eggs for fertilization, Melanie was also having the procedure done due to her history of endometriosis and the hope of maybe having a biological child of her own someday. It is later discovered there was a mix up at the clinic and Lindsay isn't Gus' biological mother, Melanie is.

And what if Lindsay had been so desperate for Melanie to use Brian's sperm, so their kids would be related by at least one parent, that she dumped Michael's ‘donation' down the toilet and substituted it with semen she extracted from condoms she stole from Brian's loft?

What, if anything, would change? Would the girls tell anyone? Would Lindsay panic and take off with ‘Brian's kids' or would she just be happy to raise them with Melanie? How would Brian react to being the father of two kids with Melanie? What would Michael do if he found out that he isn't Jenny's father?