Radio button height not uniform when some labels have subscript

When some (but not all) of the labels used for a radio buttonset have subscript (or superscript), the button heights become uneven. The bottom edge is pushed downward, presumably by the padding in the css.

<div id="test">

<label for="button1">Button1</label>

<input type="radio" id="button1" />

<label for="button2">My _bottom edge is lower</label>

<input type="radio" id="button2" />

</div>

$('#test').buttonset();