html tags stripped from blog summaries

I note that the page …/posts/, which contains summaries of the recent blog postings, strips the html tags from the text before displaying the summaries. I can live with the <h2> tag being removed, although it is not ideal. But I also have on occasion a <sup> tag, not to mention an anchor . When the <sup> is removed, the text looks weird.
I have not seen this behavior with my previous theme, so I suppose it has something to do with Vanilla. How would you suggest I change the functionality so as to leave certain tags in the summaries?