Apologies if this is caused by my outdated version of WordPress, but if it hasn't been picked up it might be worth resolving:
If you put a <!--more--> in the middle of an italicised section of text (or presumably a bold section, underlined section etc.) then everything from that point on on your front page becomes italic.
This seems to be because the "em" remains in the html for the front page, but the "/em" does not, as it is only in the main body of the post, and so not displayed on the front page due to the <!--more--> functionality.
Once I realised what was happening it was easily worked around by adding a "/em" immediately before the <!--more-->, and an "em" immediately after, but unless this is resolved others might find it as confusing as I did initially.
All the best,