Children are the only people that can be legally discriminated against and refused service in restaurants. Children should be treated the same as other diners. Anyone disruptive should be asked to leave. To assume all children will disrupt others and refuse to serve them, is discriminatory.
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Many parents have experienced the humiliation of being refused a table because they want to go out for food with their children.
Most diners (including parents) do not want children running around spoiling their dinner. But not all children run around and are disruptive - many restaurants already say 'well behaved children welcome before 8pm'. This should be the law.