www.dailymail.co.uk/news/article-2328536/Angela-Merkel-Communist-links-new-image-uniform-released.html
She studied (which in the GDR meant that she was allowed to; politically critical thinkers or people with relatives in the west not rarely had difficulties getting into university, and Leipzig was quite a good university, spiegel.de/lebenundlernen/uni/ddr-hochschulen-vor-20-jahren-studis-zur-freiheit-a-656670.html)
From above sauce:
"And for every one of the more than 50 universities in the GDR it was like: The staff was hand-picked. In Dresden or Leipzig, in Jena, Greifswald or East-Berlin often only students were allowed, that had proven their socialist loyalty or at least were able to credibly communicate it."
She was a propaganda secretary for the FDJ (GDR's youth org for adolescents, de.wikipedia.org/wiki/Agitation#Agitation_im_Staatssozialismus)
That means she was quite cosy with the system in the GDR (and my guess is she'd have gone into politics after FDJ – why become an "agitator" ?).
Just the same she was cosy pretty quickly with the CDU after the wall came down (i.e. "Wendehals" == turncoat), and became Kohl's protégé. From there, we know the rest.