NBC’s Who Do You Think You Are? (1.5/5 in adults 18-49, 7.6 million viewers) shot up a whopping 50% in adults 18-49 from last week to post its best demo result in 2 years and largest audience ever, and that is great news for ABC. That’s because the ratings for shows like WDYTYA are closely tied to the celebrity featured in each episode. Last night, it was Reba McEntire who proved her continuing drawing power just as ABC is prepping a comedy pilot with her for next fall. NBC’s ratings gains carried over to 9 PM where Grimm (1.7/5) was up 13% from last week, once again proving that it does well when its run is interrupted, something it has rarely gotten so far. Grimm was also helped by the fact that its time slot rival Fringe, which targets similar audience, is on hiatus. At 10 PM, Dateline (1.3/4) was flat.

CBS’ Undercover Boss (2.0/7, 9.6 million) was up a tenth from last week and was once again the top program of the night in 18-49. The season and almost certainly the series finale of A Gifted Man (1.4/4, 9.7 million) also was up a tenth, while Blue Bloods (1.7/5, 11.4 million), once again the most watched program of the night, was flat.

ABC’s Shark Tank (1.7/6) slipped a tenth against Undercover Boss and WDYTYA, despite the fourth reality series in the hour, Fox’s Kitchen Nightmares, airing a repeat. But both of ABC’s newsmagazines, Primetime: What Would You Do (1.7/5) and 20/20 (1.6/5) were up double digits, helping ABC (1.7/5, 5.9 million) to tie CBS (1.7/5, 10.2 million) for No.1 among adults 18-49 for the night. Fox aired all-reruns.