Here is the unpublished opinion in In re Parentage of Harker.

An excerpt:

For several reasons, we agree that the trial court placed undue emphasis on a single portion of the child’s multi-cultural heritage. First, although factor (v) required the trial court to consider the child’s significant relationships with others, his physical surroundings, his school, and “other significant activities,” see RCW 26.09.187(3)(a)(v), in promulgating this statutory factor, the legislature did not require the trial court to consider the child’s cultural heritage. Instead, RCW 26.09.184(3) provides that the trial court “may consider the cultural heritage and religious
beliefs of a child.” (Emphasis added.) That the legislature “allows,” rather than “requires” trial courts to consider cultural heritage suggests that the legislature did not intend for cultural heritage, though important, to be a determining factor in a child’s residential placement.

Second, although Harker mentioned his Native American heritage and his desire to involve his son in that culture, it was the trial court, rather than Harker, that developed the vast majority of evidence related to this cultural heritage. In addition to developing the cultural heritage component of pro se Harker’s case for him, the trial court then ignored the non-determinative nature of this factor when it expressly found that Harker would promote the child’s cultural
awareness and that this fact “weigh[ed] very heavily” in favor of making Harker the primary residential parent. III VRP at 315. Furthermore, in so ruling, the trial court ignored the lack of evidence that Arviso would interfere with Harker’s involving their child with his Native American culture. Nor did the trial court expressly consider the child’s potential involvement with Arviso’s Hispanic culture.