jQuery preventDefault
HTML
<input type="radio" id="Svar0" name="Svar" value="Yes">
<input type="radio" id="Svar1" name="Svar" value="No">
<input type="radio" id="Svar2" name="Svar" value="MayBe">
JavaScript
$(document).ready(function() {
var allowChoose = true;
$('input').click(function(e) {
if (allowChoose) {
allowChoose = false;
} else {
e.preventDefault();
}
});
});