We discuss accent mixture and the creation of idiosyncratic phonological systems in acquisition, with a focus on Scottish English. Such mixing is in addition to the relatively stable sociolinguistic systems of variation expected within a speech community, and arises when parents have radically different accents from each other or from the child's peers or other adult models. In terms of traditional geographic dialectology, there are a number of isoglosses around the Scotland/England border, but modern social mobility means that in some Scottish cities there are large numbers of families with at least one non-Scottish adult accent acting as a model for acquisition, which may feed into phonological change. Of particular interest is the influence of Southern British English accents.We exemplify the issues with two short case studies. The first concerns a child with mixed Scottish/English input in the home. His speech patterns do indeed indicate the acquisition of a mixed system. The second focuses on inter-sibling variation, looking at two sibling pairs who exemplify a different mix of accent features from each other. We examine two main diagnostics: monophthongal vs. diphthongal productions of the vowels in FACE and GOAT; and rhoticity. We also describe a parental demographic and accent attitude questionnaire as part of Case Study 2. The results support the need for speaker-by-speaker study of how incompatibility between two target systems is handled. We conclude that descriptions of mixed accents should be more common in the literature and approached on a feature-by-feature basis to help develop models of accent interference.