Do browsers send "\r\n" or "\n" or does it depend on the browser?

This question has bothered me for a million years... whenever I create a website with a textarea that allows multi-line (such as a "Bio" for a user's profile) I always end up writing the following paranoid code:

// C# code sample...
bio = bio.Replace("\r\n", "\n").Replace("\r", "\n");
bio = Regex.Replace(@"\n{2,}", "\n\n");

So, what do browsers send up for a <textarea name="Bio"></textarea> if it has multiple lines?