Do you have to wrap the Text associated with *each Radio Button* in a <label> tag?

For example, here I did not do that...
HTML Code:
	<!-- Gender -->
	<label for="gender">Gender:</label>
	<input type="radio" name="gender" value="F" <?php echo (isset($gender) && $gender == "F") ? 'checked="checked"' : ''; ?>/> Female
	<input type="radio" name="gender" value="M" <?php echo (isset($gender) && $gender == "M") ? 'checked="checked"' : ''; ?>/> Male
(As you can see, I just used the <label> tag for the Radio Button Group...)

Also, what happens if you don't have an id= for each Radio Button?