2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/72783This paper introduces a notion of 2-orthogonality for a sequence of polynomials to give extended versions of the Meixner and Feinsilver characterization results based on orthogonal polynomials. These new versions subsume the Letac-Mora characterization of the real natural exponential families having cubic variance function.Published at http://dx.doi.org/10.1214/009117904000000522 in the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org)Probability60J15 (Primary) 60E10. (Secondary)text