Annika's parents were killed or are in prison, her parents didnt abandon the kids, it looks more like they left them in the mandir to protect them and so on😆( of course my speculations)
perhaps the parents extracted a promise from Annika to forget them and protect her small sister
that's why sub-consciously Annika has deleted her past with regards to her parents
and then when her sister 'died', she lost it completely
she knows that there's nothing but pain in her past now
this is my view on why Annika isnt keen to know anything about her past...
besides when she talked with SSO in yesterday's episode, i got the feeling that she did try to find out about herself, but never got anything else from it
and of course unlike SSO, Bajaj wouldnt meet a nobody like Annika🤔