From what I understand, there are 2 sets of fermions, one left-chiral and one right-chiral. Every electron in my body can be left-handed or right-handed. Do they stay the same forever or can they change chirality? Or is it more abstract property and a single electron can not be assigned chirality like electrical charge? If my intuition is true, does it mean that some electrons in my body will never undergo weak interactions? Or can I possibly replace all fermions in my body with right-handed particles and gain, say, partial immunity to radiation? If this is true, have any measurements been made how many particles in the Universe are right or left-handed?