When Martin and Mart Helme were sworn in as lawmakers in the Estonian Parliament this week, they accompanied their broad grins with a gesture — making a circle with the thumb and index finger and holding the other three fingers outstretched.

To some, that would register as the fairly anodyne, universal signal for “O.K.” — understandable, given the celebratory mood.

But to others, the signs represented something much more sinister.

The Helmes — Mart is Martin’s father — are leading figures in the far-right Conservative People’s Party, or EKRE, which mined anti-immigrant feeling during elections in March to win 19 seats in Parliament, more than doubling its representation and earning it a place in Estonia’s coalition government.

Given that context, the gesture was interpreted as showing allegiance to the doctrine of white power, and it shocked many commentators.