Big Brother Cast Revealed – Rachel Reilly's Sister Elissa Slater Will Compete
06/20/2013 AT 03:00 PM EDT
"I've always loved Big Brother and I've always wanted the opportunity to do it," Slater tells PEOPLE. "I hope people at home see that I am in it to win it and a force to be reckoned with."
Slater, 27, is one of 16 houseguests competing for the $500,000 prize during season 15 of the CBS reality show – the largest cast ever.
"Forming an alliance is my main strategy," says the nutritionist and yoga instructor. "I definitely want to form the first girl alliance in Big Brother history that will make it to the end. I'm such a girly girl and I think it would be really fun for girls to run the game."
Slater initially planned on keeping her relation to Reilly – a two-time competitor and winner of season 13 – a secret, but her sister had different advice.
"I was like, 'That is the dumbest plan because they are going to just think you are lying or trying to keep something from them,' " Reilly says. "Elissa and I look so similar that I think it is just obvious. I think she will end up telling people."
And while Slater calls Reilly her "favorite player because everyone underestimated her," she is not planning to play exactly like her sister.
"I want to have her competiveness and focus but I don't want to play her social game because that was bad," says Slater. "I want to be socially savvy."
Slater – who will spend the summer away from her son Riley, 8, as well as her husband Brent and his three children from a previous marriage – will be joined in the '60s-style Big Brother house by fifteen other house guests. Among them: political consultant Helen Kim, 37, who applied after three months of bed rest while suffering from MRSA infection; communications professor and improv actor Andy Herren, 26, who says he will be compared to season 12's Ragan Fox; and professional inline skater and entrepreneur Nick Uhas, 28, who describes himself as "super-energetic, which could be too much for people."
Big Brother premieres June 26 on CBS.