Keira Shaylee Hammond is the first born to a whole new generation of Hammonds - three eventually followed. However, something unexpected happened - as she grew up, it was clear that the first Hammond of that generation was a Squib.
This set her apart from her siblings and isolated her in the household growing up. Since she didn't need magical education and could take care of herself and her own studies, her parents favored handling their younger children and having her serve as a pseudo-babysitter for them. She didn't mind the role, but this caused her to rebel against her parents in her early teenage years.
The once squeaky clean A+ student began skipping school, getting in with bad crowds, talking back to her parents and pretty much everyone else (except her siblings), and becoming an overall menace. No matter what her parents tried, they didn't seem to get through the teenager. The one who did was the sister closer in age, whom took it personally when Keira was verbally assaulting their parents.
This resulted in a very big argument, culminating with Keira in tears, openly admitting that she just wanted her parents to notice her doing something past getting good grades - that she didn't feel that she belonged in the family due to the lack of powers, and that her brain was the only thing they ever saw in her. This was not true and the sister made her realize this. From then on, Keira made an effort to consciously curb at least some of her mindset, and got closer to her sibling over time. Her effort was so great she wound up becoming the student council president in her high school.
This wound up having a very negative impact in Keira's life, as she would soon come to realize. She was just about to enter college when she realized she had a strong physical and romantic attraction to said sibling, whom was just 14 at the time. Disgusted with herself, she opted to move to the college's dormitories instead of staying home in an effort of creating a rift between them and forget about her.
It didn't work. Weekend lunches with the family became torture, and she became obsessed with checking for any messages she might have received while not paying attention, as well as looking for any signs of reciprocation - no matter how many times she rationalized it as wrong. Going one step further, she took her best friend, whom she knew was in love with her at the time, and slept with him; this wound up conceiving Michael. The end result was a shotgun wedding wherein she was lying through her teeth about loving the man, practically begging for this child to be the turning point.
It wasn't. She then had another child, just over a year later. It didn't work either. She then concluded her degree while her parents handled the children, and started working from sunrise to sundown.
It still didn't work.
Guilt-ridden and not wanting their children to grow up in a loveless household, she wound up getting a divorce on amicable terms. At that point, she was 25 years old, was divorced, and had two children to raise. Both parents elected to let them stay with the Hammonds as they had quite a bit of experience with the matter, while they focused on their jobs - to her surprise, that sibling she adored offered to move in so to help with rent and with setting up Keira's show. While she had most of the latter down and ready to go, she was strapped for cash, and thus reluctantly agreed to this suggestion.
One thing led to another, and during a drunken night of celebration over a very pronounced spike in viewership, the two ended up very physically displaying their attraction for one another. From then on, it became a regular thing. However, Keira is scared it will make them both end in prison, and doesn't want herself nor her sister to be ostracized from the Hammonds. As such, they have to keep leading a double life and hope nobody finds out, especially Samantha - she can read people exceptionally well, after all.