Age plays a role in how weight is distributed on the body. Disabling the age question uses a less accurate model to estimate customer bodies.
When it is a reasonable trade-off
Turning off the age question is reasonable if:
Your customers are concentrated in a narrow age range, so the accuracy loss is small.
You have evidence the question is causing drop-off in completions.
When to keep it
Keep the age question if:
You sell across a wide age range.
You sell fitted garments where landing on the right side of a size boundary matters.
Check the age group on your product information
Separate from the age question, make sure the age group setting in the product information — adult, kid or toddler — is set correctly for each size chart.
Leaving a children's chart set to adult is a common cause of sizes coming out consistently too large.