Being German, I am used to getting information about the gender of a sentence's subject in the same sentence:
Meine Freundin mag Bücher.
Here it is immediately clear that it's a female friend of mine who likes books.
In English, however, many nouns do not imply a certain gender (which makes a lot of things so much easier):
My friend likes books.
How is such a sentence perceived by a native English speaker? I'm particularly interested in the case where such a sentence is part of a story, where the reader is likely to visualize the sentence's action mentally.
Personally, I tend to imagine the subject as being male (this might be due to male profession titles and pronouns being the de-facto standard in German texts, even if the texts are not gender specific). This leads to surprises in situations like this one:
My friend likes books. She owns many of them.
Do native English speakers experience a similar surprise? (Note that this works for both genders, i.e. a female reader might be surprised if "He" owns many of them) If not, what happens instead?
Edit: Several answers point out that the same issue exists with other attributes (age, race, ...). However, in my experience, these attributes are either not fixed at all during a story (so we're fine to imagine them anyway we want) or comply with the stereo-types we have for the story's cultural environment (so the chance is high that we imagine the "right" thing). Gender, on the other hand, is almost always fixed for a story's characters, and very hard to guess in a more modern and western setting.