multiselect DataGridView rows without pressing CTRL in c#?

Question

I am new to c# and using windows forms.

I have a DataGridView control on a form and I need to allow a user to multi-select rows (when they click on a row) without using the CTRL key (no keyboard is available - they are using a touch screen) and without using check box column. I have enabled the mutli-select property.

Please help me how to do that, Thank you