Reading this reminded me of these lines from draft script.

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Michael sits at a table having a sparse lunch. He is
attended by his sister Connie, who seems to be the closest
person now living on the estate with him. We see from the
way she pampers him with his lunch, that she has fallen into
the role of a surrogate Mother-Wife. He seems older than
his years, as though his illness, diabetes, has taken its
toll.
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Is there a subtle implication of incest?