In the homily for Corpus Christi Sunday, our priest said we genuflect to the crucifix. Not exactly, we genuflect to the Blessed Sacrament! That’s what the sanctuary lamp is for, so anyone entering the church knows instantly if the Sacrament is present and knows to genuflect.
Double genuflection if the Blessed Sacramenent is exposed, as in Benediction or Adoration.