Here is the info from the link above that talks about cross reaction between Macadamia Nuts and Hazel Nuts, etc.
Macadamia nut belongs to the Proteaceae family, which are classified separately from most other tree nuts and from Peanuts.
Partial cross-reactivity has been reported between Hazel nut and Macadamia nut (4). In a study of Almond, antibodies developed to Almond were shown to be specific for Almond; however, some cross-reactivity was observed with extracts of some tree nuts and of Sesame seeds. Sodium dodecylsulfate-polyacrylamide gel electrophoresis and Western immunoblotting indicated that anti-Almond antibodies recognised proteins extracted from Black walnuts, Brazil nuts, Cashews, Hazel nuts, Macadamia nuts, Pistachios, and Sesame seeds, in addition to those from Almond (6).
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