The Propagation Proposition
| Episode Number | 12 |
|---|---|
| Season | 12 |
| Aired | 2019-01-10 |
| Overview | Penny's ex-boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard for help. Also, Koothrappali attempts to mend things with his ex-fiancée, Anu. |
| Runtime | 25 minutes |
| Absolute Number | 267 |
| Finale Type |