Hi,
Use radio button list for gender selection
Here I'm providing some example to get selected value from radio buttonlist control
<asp:radiobuttonlist id="RadioButtonList1" runat="server" xmlns:asp="#unknown">
<asp:listitem text="Male" value="1"></asp:listitem>
<asp:listitem text="Female" value="0"></asp:listitem>
</asp:radiobuttonlist>
and place below code in button click event
if (RadioButtonList1.SelectedIndex >= 0)
{
int gend = int.Parse(RadioButtonList1.SelectedValue);
}
By using gend variable you can save it in your database
All the Best