Wikipedia claims it has "no firm rules" (see WP:60 week 6), but in fact its policies are highly sensitive about a few issues. The writing of entries about people who are still alive to be affected by them is one of the biggies.
In 2005, the late journalist John Seigenthaler was the first to speak out about malicious falsehoods in his entry. Wikipedians responded first by removing the defamatory material, and second by creating the "Biographies of living persons" policy, commonly called BLP. Stated clearly, biographies should be written with great care.
The simplest method is to stick closely to the best sources available. When writing about living persons, always include a reliable source for everything. Conversely, anything without a source—even if it seems obviously favorable to the subject—must be verified, or it can be deleted without discussion first.