Continuity mistake: Right at the start of the episode, Leonard kisses Penny. When he starts kissing her his head is tilted to the right (opposite side to the wall with the camera). When they move to the camera image, his head is tilted to the left (on the side with the camera), and when they move back his head is back tilting to the right again. (00:00:30)
Continuity mistake: Penny throws Sheldon's sock down on the table, and their positions change when Sheldon picks them up, despite no one touching them. (00:05:50)
Continuity mistake: In the laundry room, Sheldon is holding a blue shirt in his hands and has a bit of extra material near his hands. When the shot changes, he is holding the shirt differently and the extra material has gone. (00:05:50)
Continuity mistake: When Sheldon is undoing a pair of socks that Penny has paired, Penny is seen holding a single sock. Camera changes and she now has nothing in her hands. This is an instant cut. No time to drop it. (00:05:50)
Continuity mistake: When Sheldon is looking at his socks that Penny paired up, his grip on them changes between shots. (00:06:00)
Continuity mistake: In the laundry room when Penny is talking to Sheldon, Sheldon takes some time arranging a blue shirt on his plastic laundry folder. Then it suddenly turns into a pair of socks, which he folds and then picks up the blue shirt again. There was not enough time for him to switch out the shirt for the socks. (00:06:30)
Continuity mistake: Leonard says that Sheldon has gone crazy and chucks his pen down on a red pad on the desk. When the shot changes, so does the position of the pen without being touched. (00:13:10)
Continuity mistake: When Sheldon is sitting with Raj in his apartment watching television, the can of soda on the table in front of him rotates itself a couple of times. (00:14:40)
Continuity mistake: When Leonard shows Penny the leaflet at the end, she is holding it in one hand in shot but with 2 as the camera changes. (00:19:50)
Suggested correction: Genes can be dormant. Which allows them to skip generations. Therefor Missy's children could actually get the "mutated" gene. This is especially true since Sheldon and Missy are twins. Also, since the episode is about who out of Leonard, Howard or Raj, Sheldon would allow to "mate" with his sister, there is the added "insurance" of getting any smart genes from any of the 3 Lothario's mentioned above.
If you are going to try to argue with a geneticist about genetics, please use the correct terms. Sheldon is not referring to a recessive gene - there is no such thing as a dormant gene - he is speaking of a randomly mutated gene. Those are the words he used. If he had inherited a homozygous recessive karotype - one recessive gene from each of his parents - then somewhere in his family tree there would similarly gifted people, in which case he would use the correct term - a recessive gene. If Missy is a heterozygotic dominant karotype possessing the recessive gene for super-genius and the dominant for ordinary intelligence then mating her with Howard, Raj or Leonard would be a waste of time as their dominant genius gene would prevent the recessive super-genius gene from being expressed in the phenotype of the resulting child. The child would be highly intelligent but not on Sheldon's standards. It doesn't matter if Sheldon does not know any of this as he refers several times to a randomly mutated gene, not a recessive one. Missy does not carry the super-genius gene. The posting is correct.
Sheldon is prone to magical thinking when necessary to preserve his obsessive need to control his environment. He may have simply ignored the flaw in his reasoning, as even the most intelligent humans do when venturing outside their ares of expertise. He may be interested in the science of genetics, but his Ph.D. in physics doesn't qualify him as an expert in that field.