What is a Genuflect?
Genuflecting is a sign of respect. It's kneeling on one knee in front of the person you wish to respect. Picture a man asking a lady to marry him.
How do you know what knee to kneel on?
Easy. You genuflect on the right knee, only to God. That's why we Catholics genuflect in front of the Tabernacle. See this picture of St. Dominic playing with Baby Jesus. Note that St. Dominic is on his right knee.
Now see the soldier genuflect to Former First Lady, Nancy Reagan. The soldier is on his left knee. BTW, the soldier is presenting the flag that draped President Reagan's coffin, to his widow.
Viva la difference.