Tanisha, 35, has been grabbing eyeballs with her increasing closeness to co-participant Armaan Kohli on the show.
Kajol says she watches 'Bigg Boss' regularly and feels the show's format is such that it brings out the worst in the person.
"I watch it regularly and I will support her because she is my sister. I don't think I have any advise for her because that place is such... It puts you in an unnatural situation and compels to get the worst reaction out of you," said Kajol who was in the capital to attend the Hindustan Times Leadership Summit.
She was accompanied by her husband Ajay Devgn to the event.
The couple chatted at length about their love story and how their marriage has worked because they are completely opposite.
"We dated for almost four years before getting married and we are best friends. I think our relation has worked only because I speak a lot and he quietly listens. I can go on for hours and he can stay mum for hours... So the secret to our happy married life is that Ajay doesn't say much," said Kajol.
Adding to this, Ajay joked, "I sometimes listen and sometimes I just pretend to listen."
The couple tied the knot on February 24, 1999 and together raise two kids - Nysa and Yug.