Theremin's linearity between grounding on body and on Earth?

Hello, I have a problum with my theremin(LV-4 theremin).  I use two ways to ground my theremin. One is grounding my theremin with three-holes-socket(the real grounding),and another is using grounding wires which connect my body and theremin.  I found that the linearity is changing, especially for high pitch(C5-C7), the second way's high pitch is more expand than the first one.  I want to know which one is the real linearity of the theremin.
Thanks, sincerely!
P.S Sorry my english is very rough.

It is assumed that the theremin is a touch-less instrument.  Therefore, any physical contact (wires, buttons, pedals) are an escape from the classic conception.  So it's more correct to accept  the "second way" as a condition for "true linearity".

But nothing stops you from experimenting.  Perhaps the first way will be more playable for you.

Thank you!!

It is assumed that the theremin is a touch-less instrument.  Therefore, any physical contact (wires, buttons, pedals) are an escape from the classic conception.  So it's more correct to accept  the "second way" as a condition for "true linearity".But nothing stops you from experimenting.  Perhaps the first way will be more playable for you.

Sorry, the second way has better linearity, especially for is range(C1-C7 -> C1-C8).  So I want to know which things change the linearity? Electric capacity?
Thanks.

which things change the linearity? Electric capacity?"

The self capacitance of human body (approx. 100 pF) which is connected in serial with so called "hand capacitance".

It slightly slows down the increase of total capacitance when the hand approaches the antenna.

When you wired your body to chassis of instrument, you exclude the body capacitance from the chain.

The "hand capacitance" is a complex value, which is a result of competition so called "intrinsic capacitance" vs. "mutual capacitance". Ask dewster, an expert on this subject who had a cognitive touchless sex with Capacitive Clara.

Thank you!!