What can I substitute for onions in a bolognese sauce?

Is there a reason such as an alergy for banishing the onion? For an authentic bolognese sauce you do need aromatics as part of your foundation. Carrots of course. Bolognese ragu is one of the few Italian sauces that cooks for a long time so the onion flavor is barely perceptable.

The white parts of some leaks finely chopped might do the trick.

Shallots