Capitalize names of relationships only when they are a part of or a substitute for a person's name. (Often this means that when there is a modifier, such as a possessive pronoun, in front of such a word, we do not capitalize it.)
"Let's go visit Grandmother today."
"Let's go visit my grandmother today."
Search Engines And Capitalization: A Case (of) Sensitive Search. By Danny Sullivan, Editor.
People spend a lot of time worrying about capitalization, especially in relation to meta tags. This is because some search engines are case-sensitive, which means a search for "Entertainment" will bring up different results than a search for "entertainment."
So what should you do? The simple answer is to relax and stick with lower case. That's because practically everyone searches in lower case. Besides that, only two search engines are completely case sensitive.
Real Life Capitalization
The example below is drawn from a real web site, which was ranked exactly the same when searching for the name of a company, regardless of the case used. It shows the number of clickthroughs, taken over four days in January 1998.
lowecase: name 82% (People tend to use lowercase)
uppercase: Name 10%
Also, keep in mind that grammatically, names should be capitalized. However, people ignore this rule when doing searches, in this example. Thus, they are even more likely not to capitalize when searching for terms that normally aren't capitalized.